1. Field of the Invention
The present invention relates to a wireless IC device applied to an RFID (radio frequency identification) system where data communications are performed using electromagnetic waves in a contactless manner, and a manufacturing method thereof.
2. Description of the Related Art
In recent years, as article management systems, there have been used RFID systems in which a reader/writer, which generates an induction electromagnetic field, and an RFID tag, which is attached to an article and stores predetermined information, communicate with each other in a contactless manner so as to transmit information (see Japanese Unexamined Patent Application Publication No. 2005-244778).
FIG. 1 is a diagram showing an example of a contactless IC tag (RFID tag) where IC tag labels are mounted on IC tag antennas, shown in Japanese Unexamined Patent Application Publication No. 2005-244778.
An RFID tag TO is formed by forming a symmetrical pair of main antenna elements 81, an auxiliary antenna element 82, and a symmetrical pair of matching parts 83 on one surface of a dielectric substrate 84.
The main antenna elements 81 are meander-type antennas defined by meandering line conductors, and are disposed on the dielectric substrate 84 symmetrically. The main antenna elements 81 occupy both end areas of the dielectric substrate 84. The auxiliary antenna element 82 is disposed between the symmetrical pair of main antenna elements 81.
The matching parts 83 are defined by meandering line conductors. Ends of the matching parts 83 are connected to inner ends of the main antenna elements 81. A wireless IC chip 86 is mounted on the other ends of the matching parts 83.
However, the contactless IC tag of Japanese Unexamined Patent Application Publication No. 2005-244778 has the following problems.
Since the IC chip is mounted on the main antennas, it may be broken when shock, stress, forces or the like is applied to the main antennas.
Since the IC chip and main antennas (matching parts) must be disposed so as to be electrically coupled to each other, the main antennas have a small degree of flexibility in the disposition position. Also, the main antennas have a small degree of flexibility in designing radiation characteristics or directivity. Also, a high mounting accuracy is required and the manufacturing process is elongated. Therefore, the cost is increased.
Since the IC chip is connected to the main antennas using a conductive material, it is difficult to demount and then reuse the IC chip or replace it with another.